Influence of dense phase carbon dioxide and pasteurization treatments on storage quality of guava puree

Guava is a good source of antioxidants and other phytochemicals, and dietary fiber. The traditional method for preserving guava puree is heat pasteurization, which degrades certain constituents that are beneficial to human health. The objective of this study was to determine the optimal conditions (pressure, % carbon dioxide, and residence time) for the pasteurization of guava puree by Dense Phase Carbon Dioxide (DPCD) process. The amount of CO₂ solubilized in the puree was measured experimentally in the range of pressure from 6.9 to 31.03 MPa at 35 °C. The experimental results were compared with the equilibrium conditions evaluated using the process simulation software Aspen Plus®. A log reduction ≥3.2 was achieved for yeast and mold count and aerobic plate count using 34.1 MPa pressure, 8 % CO₂ and a residence time of 6.9 min. Guava puree was microbiologically stable during 14 weeks of refrigerated storage at 4 °C. DPCD samples showed pH similar to fresh samples but the titratable acidity for the DPCD was higher than the untreated ones. Increases in viscosity and cloud loss were observed for the DPCD treated puree. In addition, pectinesterase activity was partially inactivated reaching 20 % reduction. DPCD processing can be used as a non-thermal treatment without deteriorating the quality of the product compared to heat pasteurization.